The invention relates to a shredder which has a cutting unit frame and at least one motor-driven cutting shaft, rotatable supported in the cutting unit frame and carrying a multiplicity of cutting disks being rotatable with the shaft for shredding an item in cooperation with a further tool, the cutting unit frame including two opposing side parts extending parallel to the cutting shaft and two fronting parts each having respective upper and lower fronting part elements attached to one another and extending between and separately attached to the side parts and internally capturing one of a pair of bearings therebetween such that the bearings rotatably mount opposite ends of the shaft in the cutting unit frame and are removable with the shaft upon removal of only the upper fronting part element of each of the fronting parts.
Such shredders are frequently employed for recycling raw materials, wherein a multiplicity of differing products are shredded with such shredders, such as for example sheet metal parts, tires or also refrigerators, to name only a few. Such prior known shredder comprises a highly stable, distortion-free cutting unit frame, in whose fronting faces are supported at least one cutting shaft, driven, for example, by an electric motor. The one cutting shaft carries a multiplicity of cutting disks, which most often carry a multiplicity of cutting heads. The cutting disks are disposed such that they are spaced apart from one another and cooperate with a further tool, such as a stationary stripper or a second cutting shaft with cutting disks rotating counter to the one cutting shaft. A cut gap provided between the cutting disks or between one cutting disk and the stripper can only be a few tenths of a millimeter in order to obtain the desired cutting result. To ensure the correct rotation of the cutting shafts without the oppositely rotating cutting disks impairing each other, the cutting unit frame is layed out correspondingly stable and distortion-free such that even when shredding very hard or tough items, no distortion occurs on the cutting unit frame, which could change the cut gap between the cutting disks.
In a prior known shredder the two cutting shafts driven in the opposite direction are supported in the two opposing fronting parts. The fronting parts themselves are structured so as to be divided in two and formed by a lower fronting part element and an upper fronting part element. This division is provided in order for the cutting shaft to be lifted out of the cutting unit frame by dismounting the upper fronting part element. The fronting part elements themselves are secured between the end regions of the two opposing side parts. The attachment of the fronting part elements on the side parts takes place with attachment bolts which penetrate through the side parts and engage laterally the narrow sides of the fronting part elements. In this prior known shredder the cutting unit frame is formed when the side parts are bolted with all four fronting part elements. Apart from other means, with the attachment bolts, inter alia also by staying the side elements with one another, a necessary adjustment and setting-up of the cutting unit frame takes place in order to be able to ensure the correct travel of the cutting disks by setting up the cut gap correspondingly.
Due to their wear, the cutting disks must be replaced at periodic time intervals. In order to keep the time during which such shredder is not used during a replacement of the cutting disks as short as feasible, in this prior known shredder the entire cutting shaft is removed from the cutting unit frame and replaced by another with new cutting disks. For this purpose the attachment bolts of the two fronting part elements must be unscrewed and those of the upper fronting part element must be taken out completely in order to be able to remove this from the cutting unit frame. However, this causes the cutting unit frame to be brought out of adjustment. Even if a replacement of a cutting shaft by a new one can be carried out in this shredder in a short time, the disadvantage becomes manifest that with each new installation of a cutting shaft, the cutting unit frame must be set up anew and must be readjusted. This may require several days.
From EP 0 667 187 B1 is known a further shredder, in which the cutting unit frame is comprised of two side parts and two integrated fronting parts. The bearings of the two cutting shafts are disposed outside of the cutting unit frame. The bearings are structured in two parts such that after the upper bearing plate has been removed, the cutting shaft can be lifted out of the bearing. The two fronting parts of the cutting unit frame have oblong cutouts through which the cutting shafts are guided under sealing. Each of the top-side mounting of the seals is realized through an aperture plate secured outside on the fronting part. Due to the integrated implementation of the fronting parts, when dismounting the cutting shafts, in this prior known shredder, the cutting unit frame does not need to be brought out of adjustment. Consequently, the replacement of the cutting shafts can take place significantly faster compared to the previously described prior art.
However, of disadvantage in the shredder according to EP 0 667 187 B1 is that bearings disposed outside of the cutting unit framexe2x80x94so-called external bearingsxe2x80x94are provided for the bearing of the cutting shafts. In particular when mounting such a shredder therefore not only the cutting unit frame must be adjusted but additionally the two external bearings, which causes considerable additional expenses for the mounting. Moreover, a replacement of the cutting shafts is complex and expensive due to the numerous connections which must be detached. Building on this discussed prior art, the invention is therefore based on the task of further developing a shredder of the stated type according to the species such that not only an adjustment but also a cutting shaft replacement can be carried out in simple manner.
This task is solved in the shredder according to the invention wherein the fronting parts are provided such that they are divided and comprise an upper fronting part element and a lower fronting part element. In the subject matter of the invention the bearings of the at least one cutting shaft are secured in the fronting parts; these bearings are also denoted as internal bearings. Each bearing is framed by the two fronting part elements of a fronting part by being captured between the upper and lower fronting part elements thereof and thus internally of the cutting unit frame. At least the upper fronting part element of each fronting part of the cutting unit frame is detachably fastened on the adjoining side parts, wherein at the front side it adjoins the two adjoining side parts. The attachment means, employed for attaching the fronting part elements to the side parts, engage the side parts at the front side. The front side of the side parts can also be widened by a flange. The two upper fronting part elements can thus be removed, independently of the lower fronting part elements, from the cutting unit frame without having destablize it or bring it out of adjustment. The reception of the bearings between the upper and lower fronting part elements of the fronting parts also leads to the fact that already after removing the upper fronting part elements the at least one cutting shaft can be lifted readily from the cutting unit frame. The capability of removing the upper fronting part elements of the cutting unit frame also permits an especially good front-side accessibility of the cutting unit frame, in particular of the lower bearing parts, if the at least one cutting shaft is disassembled. The lower fronting part element of each fronting part remains connected with the side parts of the cutting unit frame such that it retains its adjustment or fixed condition once it is set up even when the upper fronting part element is removed.
The two opposing upper fronting part elements serve for retaining the cutting shafts with their bearings in their specified seat. For this reason it is useful to develop the fronting part elements as yoke plates, which together frame the outside of the bearing(s) of one or several cutting shafts.
For the additional attachment of the two fronting part elements with one another it can be provided that these are connected one with the other through a separate bolt connection.